Fan,especially a ceiling fan with a balanced single blande

ABSTRACT

The invention provides a fan ( 10 ) with a blade ( 12 ), suitable for use as a ceiling fan. Blade ( 12 ) may be regarded as a single blade, although shaft ( 18 ) is not attached to blade ( 12 ) at one end thereof; rather, shaft ( 18 ) is attached to blade ( 12 ) at a point between first end ( 14 ) and second end ( 16 ). Blade ( 12 ) is balanced by counterweight means ( 22 ) located in blade ( 12 ). In on embodiment, blade ( 12 ) is connected to shaft ( 18 ) by means which permit angular movement, such as a teeter hinge.

FIELD OF THE INVENTION

The present invention relates to fans and, in particular, to a ceilingfan which is balanced. The invention is especially concerned with thetype of ceiling fan which may be regarded as having a single blade.

BACKGROUND OF THE INVENTION

Single blade ceiling fans are desirable because, potentially, they mayproduce less drag, thereby increasing the efficiency of the fan. Thismeans that greater air flow may be accomplished at lower rotationalspeeds. Another potential advantage with a single blade is that theweight of the fan may be reduced, thus allowing the span of the blade tobe of a larger dimension, compared to a conventional blade for amulti-bladed fan.

However, there have been problems in balancing single-blade fans.Counterweights have been applied to the shaft of the fan, or oppositethe mass of the blade. An attempt to address the problem has been madein U.S. Pat. No. 6,726,451, where the ceiling fan blade mountingarrangement produces a centre of rotational gravity that lies outsidethe vertical axis of the rotating fan.

It is an object of the present invention to provide a ceiling fan whichcan be balanced both statically and dynamically, for stabilised rotationat high and low rotational speeds. It is also an object of the presentinvention, in a preferred embodiment, to provide a ceiling fan which canbe an architectural feature, being aesthetically pleasing. In thepreferred embodiment, the single bladed fan has a blade similar to theshape of a sycamore seed pod, and thus can have a sculptured shape,which may be appreciated even when the fan is not in use. It is believedthat such a shape has aerodynamic advantages compared to the shape of aconventional blade.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention provides a fan including a bladehaving a first end, a second end, a leading edge and a trailing edge,the blade being rotatable by a shaft connected to a motor, wherein theblade is balanced by counterweight means, at least some of which islocated in the blade.

The fan of the invention is preferably a ceiling fan but is not limitedthereto.

The invention also provides a blade for a fan, the blade having a firstend, a second end, a leading edge and a trailing edge, the blade beingadapted for rotation by a shaft connected to a motor, wherein the bladeincludes counterweight means.

The blade may be constructed of any suitable material. The material maybe a solid low density material or a high density material, such asmetal, polymer or wood. The blade may be made from a thin rigid skinfilled with foam reinforcing, such as self-skinning polyurethane.Preferably, the fan is made by extrusion blow moulding or reactioninjection moulding or other suitable technique, such as metal casting.

Preferably, the blade is an irregular sculptured form. Even morepreferably, the blade takes the form of or is adapted from the shape ofa sycamore seed pod. The blades in the drawings below are adapted fromthe shape of a sycamore seed pod. Such a blade is not flat as manyconventional fan blades are, but has curves and contours.

In this embodiment, the blade has an aerofoil cross section, withvarying vertical thickness from the leading edge to the trailing edge.The aerofoil part of the blade is designed to create less turbulence anddrag in its wake. It may require less energy to rotate it about itsvertical axis compared to a conventional flat blade and it may alsocreate less wind noise. The aerofoil design may also create higherairflow at lower speeds, compared to conventional ceiling fans.

The blade in this embodiment may be wider than many conventional fanblades. At low speed, a longer chord length aerofoil section is moreefficient. The first and second ends are shaped to be curved—preferablyelliptical. It is known that aircraft wings with elliptical wing tips(in plan view) produce less turbulence than square ended wing tips atlow speed.

In this preferred embodiment, the blade is not linear in plan view butis angled. In this configuration, there is an angle of approximately 170degrees between the first end and the second end.

The shaft and the motor may be of any suitable shape or arrangement.Preferably, the blade is attached to the shaft at a connection pointlocated between the first end and the second end. It is also preferredthat the connection point is closer to the second end than to the firstend. Where the blade is bent so that there is an angle of approximately170 degrees between the first end and the second end, it is preferredthat the connection point is at or located close to the angle of bend.

It will be appreciated that the blade of the fan of the presentinvention may be regarded as a single blade because, although theconnection point is preferably located between the first end and thesecond end, being closer to the second end than to the first end, thewhole blade is a single unit. Another view may be taken of the blade:the portion of the blade from the connection point to the first end maybe regarded as the primary blade and the portion of the blade from theconnection point to the second end may be regarded as a pod, in view ofthe similarity to a sycamore seed pod. The pod preferably has itsleading edge higher than its trailing edge. The pod may not contributegreatly to air flow provided by the fan of the invention. However, thepod may provide aero dynamic lift which can partially balance aerodynamic lift created by the primary blade. In addition, the pod asillustrated in the drawings, below, may be designed to create minimumturbulence in its wake, in order to minimise the energy required toovercome its aero dynamic drag.

The organic form shape, profile and relative orientation of the primaryblade and pod of the blade of the invention in this embodiment have beendesigned to allow the incorporation of at least some of thecounterweight means within the form of the blade. The purpose of this isto avoid interruption of the continuous sculptural surface of the bladeof the invention whilst allowing the position of the centre of gravityof the blade to be located within the blade.

In the embodiment under discussion, the blade of the invention has beendesigned so that incorporation of at least some of the counterweightmeans in the pod causes the centre of mass of the blade of the inventionto lie at a point within the blade in top plan view. In addition, theposition and mass of the counterweight means may be adjusted to ensurethat the combined centre of mass of the blade of the invention and thecounterweight means is located on the vertical axis of rotation of theblade of the invention.

In an especially preferred embodiment, the blade is connected to theshaft by means adapted to permit angular movement of the blade relativeto the shaft. Preferably, these means include or comprise the type ofhinge known as a teeter hinge, an example of which is illustrated in thedrawings.

It is also preferred that the centre of mass of the blade of theinvention and the counterweight means is located within the body of theblade of the invention, when the blade is viewed in front elevation. Theshape, profile and relative orientation of the primary blade and pod maybe determined to ensure that the centre of mass is sufficiently farwithin the blade form to allow all the components required to permitangular movement of the blade relative to the shaft to be located withinthe blade without compromising the sculptural integrity of the bladeform.

The counterweight means preferably includes at least one discrete massof material. The counterweight means may comprise two or more discretemasses of such material. All the counterweight means may be located inthe blade. Alternately, some of the counterweight means may be locatedin the blade and some elsewhere such as on the shaft. The material ofone discrete mass may be the same as or different from the material ofanother discrete mass in the same fan. In one embodiment, thecounterweight means is made of a material having a mass greater thanthat of the material of the blade. In another embodiment, thecounterweight means is made of a material having a mass lesser than thatof the material of the blade. In yet another embodiment, thecounterweight means is provided by increasing wall thickness within theblade, for example during manufacture. For example, the blade may bemanufactured by extrusion blow moulding. During manufacture, the wallthickness of selected parts of the blade may be increased in order toprovide all or some of the counterweight means.

By way of another example, a blade may be moulded in two halves, such astop and bottom, by a reaction injection moulding process or othersuitable technique, such as metal casting—aluminium or magnesium,fibreglass layup or wood shaping, with different, varying wall sectionsas required to provide some or all of the counterweight means, prior tojoining the two halves to create the complete blade.

Preferably, the location of at least some of the counterweight means isadjustable, so that compensation can be made for manufacturingtolerances. Preferably also, additional counterweights may be added tothe fan of the invention for tuning the balance during manufacture. Inone embodiment, these are located under a removable cover on the blade.The same cover can cover a cavity into which some or all of thecounterweight means may be inserted. Such a cover may be sculpted tomatch the surface form of the blade or may be a simple flat or roundinfill, on the top surface of the blade.

Of course, any counterweight means located in the blade may be assembledinto a pocket in the exterior of the blade (with or without a cover) ormoulded into the surface of the blade (with or without a cover).

Where all the counterweight means is not located in the blade, it ispreferred that part of the counterweight means is located on the shaft.

It is preferred that some or all of the counterweight means is locatedalong the leading edge of the blade. Part of the counterweight means maybe located along the leading edge and part along the trailing along theblade.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in connection with certainnon-limiting thereof as set out in the accompanying drawings, in which:

FIG. 1 is a side elevation of a first embodiment of a ceiling fan,viewed from the trailing edge;

FIG. 2 is a side elevation of the fan of FIG. 1, viewed from the leadingedge;

FIG. 3 is a side elevation of a second embodiment of fan, viewed fromthe leading edge;

FIG. 4 is a side elevation of a blade for a further embodiment of aceiling fan, viewed from the leading edge;

FIG. 5 is a top plan view of the blade of FIG. 4;

FIG. 6 is a perspective view of the blade of FIGS. 4 and 5, cut away atthe second end to show internal construction;

FIG. 7 is a top plan view of a further embodiment of a blade;

FIG. 8 is a top plan view of the second embodiment of a blade of FIG. 3;

FIG. 9 is a perspective view of a further embodiment of a blade whichincludes a teeter hinge;

FIG. 10 shows in more detail the connection point and part of the teeterhinge of the FIG. 9 embodiment;

FIG. 11 shows the second end of the blade of FIGS. 9 and 10, withcounterweight means within the blade in dotted outline;

FIG. 12 is a partial cross-sectional view of the blade of FIGS. 9, 10and 11 taken along the line A-A of FIG. 10;

FIG. 13 shows cross-sectional detail of the blade taken along the lineB-B of FIG. 10; and

FIG. 14 shows the teeter hinge and connection point illustrated insectional view in FIG. 13

BEST MODES OF CARRYING OUT THE INVENTION

Referring first to FIG. 1, ceiling fan 10 has a blade 12 which can beregarded as a single blade having first end 14 and second end 16. Blade12 is sculptured in a form similar to that of a sycamore seed pod. It iscurved and designed to provide a downward draught when it rotatesclockwise (as viewed from above).

Blade 12 is rotatable by a shaft 18, connected to an electric motor (notshown) within motor cover 20.

As can be seen from FIGS. 1 and 2, blade 12 is irregular in shape and isfixed to shaft 18 closer to second end 16 than to first end 14.

In this embodiment, the counterweight means is comprised of a balancingweight 22 located along leading edge 24 of the primary blade (that partbetween shaft 18 and first end 14) and along the trailing edge of thepod (that part between shaft 18 and second end 16) and close to secondend 16. Balancing weight 22 is made from a material which is of greaterdensity than the material of blade 12. Weight 22 comprises a singlediscrete mass and is moulded to follow the contours of blade 12 so thatit is unobtrusive.

Because there is no counterweight attached to shaft 18, motor cover 20does not need to be enlarged to accommodate any such weight, and indeedmay be somewhat smaller than that illustrated.

FIG. 3 shows a similar embodiment to the embodiment in FIGS. 1 and 2 andthe same numbers are used for the same parts as in FIGS. 1 and 2. In theFIG. 3 embodiment, a counterweight 28 is located in blade 12 very closeto second end 16. In this embodiment, however, weight 28 is somewhatsmaller in mass than weight 22 of FIG. 2. There is a second discreteweight 30 (not visible in the figure) attached to shaft 18. Thecombination of the weights 28 and 30 balances blade 12 when rotating.

If desired, weight 30 on shaft 18 could be divided into two masses anddistributed around shaft 18.

Referring now to FIGS. 4, 5 and 6, although this is a differentembodiment from the embodiment of FIGS. 1 and 2 and the embodiment ofFIG. 3, the same part numbers will be used where the parts are the sameor very similar. In this embodiment, blade 12 has substantiallyelliptical first end 14, substantially elliptical second end 16, leadingedge 24 and trailing edge 26. As shown by the plan view of FIG. 5, blade12 is curved at leading edge 24 and there is an angle of approximately170° between first end 14 and second end 16. Located at approximatelythe bend point is connection point 32. In this embodiment, connectionpoint 32 is a circular aperture adapted to receive shaft 18 (not shown).Connection point 32 may be of any other suitable shape.

Blade 12 includes two discrete masses by way of counterweight means,first mass 34 and second mass 36. Each of masses 34 and 36 is insertedwithin blade 12. Part of second mass 36 can be seen in FIG. 6, insertedin cavity 38. Cover 40 covers first mass 34 and cover 42 covers secondmass 36. Each of covers 40 and 42 is removable, so that the mass in theunderlying cavity may be removed or changed as appropriate.

It will also be noted from FIG. 6 that blade 12 is generally hollow,being made of thermoplastic polymer material, such as ABS or highdensity polyethylene.

The embodiment in FIG. 7 is similar to that in FIGS. 4, 5 and 6, exceptthat first 34 and second mass 36 are replaced by a single mass 44.

The FIG. 8 embodiment shows in top plan view the embodiment discussedabove in connection with FIG. 3.

In the fiber embodiment shown in FIGS. 9, 10 and 11, a single discretemass or a plurality of masses may be inserted in cavity 48 covered bycover 50. Cavity 48 is extended in this embodiment to accommodateconnection point 32 and teeter hinge 52, discussed in more detail inconnection with FIGS. 12, 13 and 14 below.

Shown in ghosted outline in FIG. 11 is a single discrete mass 54suspended within blade 12 by bracket 56.

Details of teeter hinge 52 can be seen in FIGS. 12, 13 and 14. Teeterhinge 52 can be applied to any of the embodiments illustrated herein inFIGS. 4, 5, 6, 7, 9, 10 and 11.

Teeter hinge 52 has cross bar 58 originally attached or integral with(as in this case) plates 60 and 62. Cross bar 58 includes screw holeapertures 64 into which are fitted screws 66 which serve to secure crossbar 58 to blade 12 (refer FIG. 13).

Connection point 32, which connects blade 12 to shaft 18 (not shown) hastail 68. Aperture 70 in tail 68 receives pivot pin 72 to connect tail 68pivotably to plate 60 and 62.

As can be seen from FIGS. 13 and 14, there is a small amount ofclearance between the inner ends of cross bar 58 and tail 68, so thatconnection point 32 can pivot to a small extent around pivot pin 72.

Blade 12 and the location of the counterweights are designed so that thecentre of mass of blade 12 (when viewed in plan) is locatedapproximately in the location of connection point 32 and drive shaft 18(not shown). Also when viewed in plan, the pivot axis is perpendicularto a line drawn from the axis of rotation of the balanced blade to thecentre of lift of the blade portion of the balanced blade. The pivotaxis is also aligned with the horizontal plane. The tip of blade 12 isthus free to move in a vertical direction by rotating about the pivot,but is constrained to rotate only in the plane in which the aerodynamiclift force of the blade is acting, thus maintaining the correct angle ofattach of the blade.

This is in contrast to conventional fans, where the blades are generallyrigidly connected to the motor housing or drive shaft.

It will be appreciated that the aerodynamic centre of blade 12—the pointat which lift is deemed to act—will vary, depending on air speed ofblade 12 and also on the pitch of blade 12. The aerodynamic force onblade 12 is composed of both lift from blade 12 and also of lift anddrag from blade 12, including lift and drag from the part of blade 12near second end 16. It is preferred that the combined centre of actionof these forces is the point which is used to define the line to whichthe pivot axis is perpendicular. The aerodynamic forces involved arerelatively small and consequently the calculation of the angle of thepivot axis may be represented by a range of values.

Because blade 12 is suspended at the centre of mass on the pivot, blade12 is free to find its own balance—the position where the centre of masslies on the vertical axis of rotation and the principal axes of inertiaof the centre of gravity of balanced blade 12 lie in the vertical andhorizontal planes. It is believed that if blade 12 were rigidly mountedand were balanced such that the principal axes of inertia of the centreof gravity were not in the horizontal/vertical planes, even though thecentre of gravity might be on the vertical axis, the centrifugal forceswould not be balanced and rotation of the blade would shake the bearingsof the motor.

When blade 12 is supported at the centre of mass of the balanced blade,and blade 12 is allowed to “self level” because of teeter hinge 52, ithas been found that the mass of blade 12 does not impart unwantedcentrifugal forces to shaft 18 which would cause blade 12 to run offcentre or wobble, cause unwanted vibrations or wear within the motorand/or transmit undue stresses to the mechanism used to fasten the fanassembly to the ceiling. Because the pivot is incorporated at the centreof mass, blade 12 can rotate about this freely. The aerodynamic forcesacting on blade 12 cause blade 12 to rotate until the aerodynamic forcesare matched by the gravitational and centripetal forces acting on blade12. Thus, at any given speed, first end 14 will rise until the positionis found at which the aerodynamic forces and the gravitational andcentripetal forces acting on blade 12 are in balance. Any bending momenton shaft 18 may thus be eliminated or minimised, and fan 10 may runsmoothly with no or minimal out-of-balance forces being transmitted toshaft 18, etc.

INDUSTRIAL APPLICABILITY

The fan of the invention provides a worthwhile addition to fantechnology, especially where ceiling fans are involved. The fan of theinvention can be presented in a modem, streamlined form which can causemovement of a greater is volume of air with less rotational speed.

1. A blade for a fan comprising: a first portion having a first end; asecond portion having a second end, the second end opposed to the firstend; and at least one counterweight coupled to one of the first portionand the second portion, both the first and the second portions areadapted to provide aerodynamic lift.
 2. The blade of claim 1, whereinthe first portion has a first leading edge and a first trailing edge;the second portion has a second leading edge and a second trailing edge;and the aerodynamic lift provided by the second portion at leastpartially balances the aerodynamic lift provided by the first portion.3. The blade of claim 1, further comprising a connection point locatedbetween the first end and the second end, the connection point forcoupling to a shaft.
 4. The blade of claim 3, wherein the connectionpoint is located at a junction between the first and the secondportions.
 5. The blade of claim 3, wherein the center of massapproximately aligns with the connection point.
 6. The blade of claim 3,wherein the connection point is closer to the second end than the firstend and at least one counterweight is located in the second portion. 7.The blade of claim 3, wherein an angle of approximately 170 degreesbetween the first end and the second end, and the angle being proximatethe connection point.
 8. The blade of claim 3, further comprising avariable pitch connector coupled to the connection point, the variablepitch connector permits angular movement relative to a shaft whencoupled thereto.
 9. The blade of claim 8, wherein the variable pitchconnector includes a teeter hinge.
 10. The blade of claim 8, wherein thevariable pitch connector is located proximate to the center of mass ofthe blade.
 11. The blade of claim 8, further comprising a shaft coupledto the variable pitch connector, and a fan motor coupled to the shaftfor rotationally driving the shaft, wherein at any given speed ofrotation, the first end will rise until a position is found at which theaerodynamic, gravitational and centripetal forces acting on the bladeare balanced to minimize or eliminate any bending moment on the shaft.12. The blade of claim 11, wherein a point on the first leading edge isconstrained to rotate about the variable pitch connector in a plane inwhich the aerodynamic lift force of the blade on the first leading edgeis acting to maintain the correct angle of attack of the blade.
 13. Theblade of claim 11 wherein, when viewed in plan, the axis of the variablepitch connector is perpendicular to a line drawn from the axis ofrotation of the blade when balanced to the center of lift of the firstportion.
 14. The blade of claim 1, wherein all of the at least onecounterweights is located in the first and second portions.
 15. Theblade of claim 11, wherein part of the at least one counterweight islocated on the shaft.
 16. The blade of claim 2, wherein some or all ofthe at least one counterweight is located along the first leading edgeof the blade.
 17. The blade of claim 2, wherein some of the at least onecounterweight is located along the first leading edge of the firstportion and some of the at least one counter weight is located along thefirst trailing edge of the first portion.
 18. The blade of claim 11,further comprising a mounting plate coupled to the fan motor forselectively attaching to a ceiling.
 19. (canceled)
 20. (canceled)
 21. Afan assembly comprising: a blade comprising: a first portion having afirst end; a second portion having a second end, the second end opposedto the first end, the blade adapted to provide aerodynamic lift whenrotationally driven; and a connection point located between the firstend and the second end; a shaft; a variable pitch connector coupled tothe connection point of the blade and to the shaft, the variable pitchconnector permits angular movement relative between the shaft and theblade; at least one counterweight coupled to either of the blade and theshaft; and a fan motor coupled to the shaft for rotationally driving theshaft.
 22. The fan of claim 21, wherein at any given speed of rotationwhen driven by the motor, the first end of the first portion of theblade will rise until a position is found at which the aerodynamic,gravitational and centripetal forces acting on the blade are balanced tominimize or eliminate any bending moment on the shaft.